3,4-dihydro-1-methylpyrazino(1,2-b)-1,2-benzothiazin-11(2h)-one 6,6-dioxides

ABSTRACT

THE COMPOUNDS HEREIN ARE 3,4-DIHYDRO-1-METHYLPYRAZINO(1,2-B)-1,2-BENZOTHIAZIN-11 (2II)-ONE 6,6-DIOXIDES, USEFUL FOR THEIR ULTRA-VIOLET ABSORBING PROPERTIES.

United States Patent 3,787,399 3,4-DIHYDRO 1 METHYLPYRAZINO[1,2-b]-l,2-BENZOTZIN-11(2@-ONE 6,6-DIOXIDES Chris Royce Rasmussen, Ambler, Pa.,assignor to McNeil Laboratories, Inc. No Drawing. Filed Oct. 2, 1972,Ser. No. 294,117 Int. Cl. (307d 93/02 US. Cl. 260-243 R 2 ClaimsABSTRACT OF THE DISCLOSURE The compounds herein are3,4-dihydro-l-methylpyraz1no[1,2-b] 1,2 benzothiazin-ll(2g)-one6,6-dioxides, useful for their ultra-violet absorbing properties.

This invention relates to novel 3,4-dihydro-l-methylpyrazino[1,2-b]1,2-benzothiazin-1l(zgyone 6,6-dioxides and the preparation thereof.Said compounds may be represented structurally as follows:

Ill

wherein R is a member selected from the group consisting of hydrogen,loweralkyl, Z-hydroxyethyl, 2-cyanoethyl, and B-phenethyl. The reactionis conducted in a suitable organic solvent such as, for example, a loweralkanol, e.g., methanol, ethanol, propanol, isopropanol, butanol, andthe like; an ether, e.g., ethyl ether, tetrahydrofuran, dioxane, and thelike; dimethylformamide; dimethylsulfoxide; and the like. This reactionmay be illustrated as follows:

R l N N (I) an, Q

The compounds of this invention absorb ultraviolet (U.V.) light and areuseful as U.V. screening materials. For example, the compound of FormulaI wherein R is hydrogen has e=10,700 at -=383 nm. Because of theirgeneral solubility in organic materials, they may be used asU.V.-absorbers in plastics and resins, such as, for example,polystyrene, polyethylene, polyacrylics (e.g., methacrylate resins,polyacrylamides, polyacrylonitrile fibers, etc.), polyamide (e.g. nylon)fibers, and polyester fibers. The inclusion of about 0.0l-5.0 percent ofthe absorber, based on the polymer weight, is usually sufficientPatented Jan. 22, 1974 to render protection against U.V. light, such asin plastic films, filters, etc. The absorbers may be incorporated intothe mixture of monomers before polymerization to form the polymer orthey may be incorporated into the polymer at other stages during itshandling, as by milling into the polymer together with other compoundingingredients, or during the spinning of the polymer into fibers, etc.

The following examples are intended to illustrate, but not to limit, thescope of the present invention.

EXAMPLE I 3,4-dihydro-l-methylpyrazino[ 1,2-b] 1 ,2-benzothiazin-l 1(215) -one 6,6-dioxide A solution of 23.9 g. (0.1 mole) of3-acetyl-4-hydroxy- 2 I;I -l,2-benzothiazine 1,1-dioxide in ml. ofdimethylformarnide is stirred while 4.3 g. (0.1 mole) of aziridine isadded. After the reaction mixture is heated on a steam bath for onehour, the solvent is removed in vacuo to give a thick, dark tar.Trituration of this tar with acetone yields a small crop of solid, whichis collected after being allowed to stand for 15 hours. The product istwice recrystallized from water-dirnethylsulfoxide to give the product,3 ,4-dihydro-1-rnethylpyrazino[ 1,2-b] -l ,2-benzothiazin-11(2E)-one6,6-dioxide, as a yellow solid, M.P. 285 C. (dec.).

Analysis.-Calcd. for C H N O S (percent): C, 54.53; H, 4.58; N, 10.60;S, 12.13. Found (percent): C, 54.09; H, 4.79; N, 10.21, 10.41; S, 12.16.

EXAMPLE II The procedure of Example I is repeated except that anequivalent amount each of N-hydroxyethyl-, N-phenethyl-, N-cyanoethyl-,and N-ethyl-aziridine is used in place of the unsubstituted aziridineused therein to yield, as respective products:

3,4-dihydro-2-hydroxyethyl-l-methylpyrazino 1,2-b1- 1,2-benzothiazin-1 12 E -one 6,.6-dioxide;

3,4-dihydrol-methyl-2-phenethylpyrazino 1,2-b

1,2-benzothiazin-11 (25;) -one 6,6-dioxide;

3 ,4-dihydro-2-cyanoethyl- 1-methylpyrazino[ l,2-b]- 1,2-benzothiazin-11 2E)-one 6,6-dioxide; and

3,4-dihydro-2-ethyll-methylpyrazino 1,2-b -1 ,2-benzothiazin-l 1 (2 11)-one 6,6-dioxide.

What is claimed is: 1. A 3,4dihydro-1-methylpyrazino[1,2-b]-1,2-benzothiazin-ll(2g)-one 6,6-dioxidehaving the formula:

wherein R is hydrogen, loweralkyl, cyano loweralkyl, hydroxy loweralkyl,or phenyl loweralkyl.

2. 3,4-dihydro 1 methylpyrazino[1,2-b]-1,2-benzothiazin-l1 (2 )-one6,6-dioxide.

References Cited UNITED STATES PATENTS 3,408,347 10/1968 Shavel et a1260243 JOHN M. FORD, Primary Examiner US. Cl. XR.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,787,399 Dated J n y 97h I c fl Chris Royce Rasmussen It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

In column 1, Formula 11, the formula should read Signed and sealed this30th day of July 1974.

(SEAL) Attest:

McCOY M. GIBSON, JR. 0. MARSHALL DANN v Attesting Officer Commissionerof Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PatentNo. I 3,7 7, 399 Dated January 97 Inventor(s) C ris Royce Rasmussen Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

In Column 1, Formula. :1, the formula. should read 0 u-CH (SEAL) Attest:

McCOY M. GIBSON, JR. C. MARSHALL DANN Attesting Officer Commissioner ofPatents

